Physico-Chemical Properties along Soil Profiles of Two Dominant Forest Types in Western Himalaya

Physico-chemical properties of soil of two dominant forest types in Western Himalaya, viz. oak (Quercus leucotrichophora) and pine (Pinus roxburghii) across three soil depths, and winter and rainy seasons were analysed. In general, all the soil parameters, viz. soil moisture, water-holding capacity, organic carbon and total nitrogen decreased significantly with increasing soil depth in both the forests. However, pH did not show any trend with soil depth. All the soil physicochemical parameters were found significantly higher for oak forests compared to pine forests. The topsoil layer (0-30 cm depth) of both the forests had high concentration of soil organic carbon (SOC) and total N. Shallower distribution of the most limiting nutrients for plants such as N was in agreement with earlier reports. A declining nutrient concentration with increasing soil depth may explain that the zone of accumulation of nutrients is not well established in the forest soils of this mountainous region due to strong leaching effect. With regard to nutrient extraction from deeper soil layers, the deep-ischolar_mained oak forest has competitive advantage over the shallow-ischolar_mained pine forest. Considering that SOC stored in the surface layer is more vulnerable and less stable than that in the deeper layers, the topsoil of these forests should be protected to minimize the risk of large carbon release. The oak forests should be given priority over the pine forests in afforestation and conservation programmes to sequester and stock high amounts of carbon in the soil pool and contribute towards mitigation of climate change impacts.